The invention relates to a truck with a refrigerated compartment, equipped with a dedicated refrigerating system, and a driver cabin.
Many vehicles, including trucks are now equipped with air conditioning units which allow cooling down the air in the vehicle cabin. When trucks are stopped with the engine shut down, the driver of the truck cannot activate the air conditioning system of the truck if it is powered by the engine. Therefore, if the truck is parked in a warm place, the cabin of the truck can become uncomfortable for the driver. In any case, vehicle air conditioning units require a substantial amount of energy to cool down the cabin of a truck. This is even more true due to the fact that these refrigerating units need to be of a comparatively small size and should not be too expensive, so that in many cases their inherent efficiency is not optimum.
Trucks equipped with a refrigerated compartment, which can be mounted on the truck itself or in a trailer, are usually equipped with a refrigerating system dedicated to the refrigerated compartment. Due to the much bigger cooling power required for refrigerating the compartment, these refrigerating systems are usually much more bulky already than conventional vehicle air conditioning units. The vast majority of such refrigerating systems are of the vapor compression type where a refrigerant flows in closed cycle circuit comprising a compressor, a condenser, an expander and evaporator. Systems for refrigerating big compartments may comprise a dedicated internal combustion engine. Nevertheless, other systems exist which are based on an mere open loop expansion of pre-compressed fluid such as nitrogen or carbon dioxide store under high pressure in a dedicated reservoir, such as described in EP-1,653,355. In any case, the temperature of the refrigerated compartment is maintained at a substantially constant value, at any time, by the refrigerating system, which is independent from the air conditioning system of the cabin of the truck if the cabin is so equipped.
As the temperature of refrigerated compartments is much lower than the temperature required in the cabin for the comfort of the driver, the refrigerating system of the compartment can be used to control the temperature of the cabin without influencing too much the temperature in the refrigerated compartment. To this end, it is known from DE-A-101 42 546 to use a heat exchanger installed in the refrigerated compartment to refresh an air flow coming from the cabin. This refreshed air flow is then sent back and blown into the cabin. The system has a single air to air heat exchanger where the air of the cabin and the air of the refrigerated compartment can exchange heat. Such system may allow dispensing with a dedicated cabin refrigeration system.
This technique needs ducts of a large diameter running from the cabin to the refrigerated compartment to obtain enough air flow, which may prove to be not convenient when the refrigerated compartment is carried by a trailer or a semi-trailer which exhibits ample movements with respect to the cabin when the vehicle is operated. Moreover, the air/air heat exchanges do not provide a satisfying efficiency and carrying low thermal energies by air induces relatively high energy losses.
An aspect of this invention aims at proposing a new truck having a refrigerated compartment equipped with a dedicated refrigerating system and a driver cabin, which allows to efficiently use the refrigerating system to refresh the cabin when the air conditioning system of the cabin is deactivated due to the idle state of the engine of the truck.
To this end, an aspect of the invention concerns a truck with a refrigerated compartment equipped with a dedicated compartment refrigerating system and a driver cabin. This truck is characterized in that the driver cabin is equipped with a least a first heat exchanger adapted to cool an air flow directed to the cabin, and wherein it comprises a compartment heat exchanger located in the refrigerated compartment and adapted to cool a heat transfer liquid sent to the first heat exchanger through a heat transfer liquid circuit connecting said first heat exchanger to said compartment heat exchanger.
Thanks to an aspect of the invention, a heat transfer liquid is cooled in the refrigerated compartment and driven to a heat exchanger installed in the cabin, in order to refresh the temperature of the cabin, for example in case an air conditioning system of the cabin does not operate, in case it is more efficient to use only the compartment refrigerating system than a cabin refrigerating system, or simply in case the cabin is devoid of any air conditioning system. The use of a heat transfer liquid induces a high heat transfer efficiency in both the first heat exchanger and the compartment heat exchanger, and small diameter hoses can be used to convey the liquid front the compartment to the cabin, which reduces the efficiency losses during the circulation of the heat transfer liquid.
According to further aspects of the invention which are advantageous but not compulsory, such a truck may incorporate one or several of the following features:
The heat transfer circuit comprises flexible hoses between the cabin and the refrigerated compartment.
The refrigerated compartment comprises a cold storage block thermally connected to the heat transfer liquid circuit.
The first heat exchanger is associated to a ventilation system of the cabin comprising several spaced apart air outlets.
The first heat exchanger is associated to a ventilation system which in installed inside a dashboard of the vehicle.
The first heat exchanger is associated to an auxiliary ventilation system installed in a living space of the cabin, and adapted to ventilate said living space.
The truck comprises a cabin dedicated air conditioning system adapted to cool an air flow directed to the cabin.
The air conditioning system of the cabin comprises an evaporator and the first heat exchanger and the evaporator are associated to a same ventilating system.
The air conditioning system of the cabin comprises an evaporator and a secondary heat transfer circuit having a secondary heat exchanger able to exchange heat with the evaporator, and wherein the first heat exchanger is connected to both the compartment heat exchange circuit and the secondary heat exchange circuit.
The truck comprises means to selectively connect the first heat exchanger to the compartment heat exchanger or to the secondary heat exchanger.
The means to selectively connect the first heat exchanger to the compartment heat exchanger or to the secondary heat exchanger comprise an electronic, control unit adapted to control valves means.